Flow over an Airfoil- Step 6

Step 6: Analyze Results

Plot Velocity Vectors

Let's see the velocity vectors along the airfoil.

Display > Vectors

Use the default setting by clicking Display.

(Click picture for larger image)

As can be seen, the velocity of the upper airfoil is faster than the velocity on the lower airfoil.

(Click picture for larger image)

On the leading edge, we see a stagnation point where the velocity of the flow is nearly zero. The fluid accelerates on the upper surface as can be seen from the change in colors of the vectors.

(Click picture for larger image)

On the trailing edge, the flow on the upper surface decelerates and converge with the flow on the lower surface.

Plot Pressure Coefficient

Pressure Coefficient is a dimensionless parameter defined by the equation
where 
is the static pressure,
is the reference pressure, and 
is the reference dynamic pressure defined by
. The reference pressure, density, and velocity are defined in the Reference Values panel in Step 5. Please refer to FLUENT's help for more information. Go to Help > User's Guide Index for help.

Plot > XY Plot...

Change the Y Axis Function to Pressure..., followed by Pressure Coefficient. Then, select airfoil under Surfaces.

Click Plot.

(Click picture for larger image)

The negative part of the plot is upper surface of the airfoil as the pressure is lower than the reference pressure.

Plot Pressure Contours

Plot static pressure contours.

Display > Contours...

Select Pressure... and Static Pressure from under Contours Of. Click Display. Check also the Filled and Draw Grid under Options menu.

(Click picture for larger image)

From the figure, we see that in one grid, there is no more than 3 different pressure contours which suggests that our mesh is fine enough.

How can we compare the pressure contour with velocity vector plot? We see that the pressure on the upper surface is negative while the velocity on the upper surface is higher than the reference velocity. Whenever there is high velocity vectors, we have low pressures and vise versa. The phenomenon that we see comply with the Bernoulli equation.

Comparisons

With our simulation data, we can now compare the Fluent with experimental data. The summary of result is shown in the table.

Go to Step 7: Refine Mesh